Patent Literature 1 discloses a technique which corrects position information received from a nearby vehicle by vehicle-to-vehicle communication or the like using map data. This kind of technique is also known as a map matching technique. In the map matching technique, when the position information of the nearby vehicle shows a position away from a road, the position information is corrected to show that the nearby vehicle is present on the road.
A drive assist system which assists a driving operation by a driver using the position information of a nearby vehicle has also been proposed. This kind of drive assist systems includes a drive assist system which displays the relative positions of the nearby vehicle and a host vehicle, a drive assist system which determines the possibility of a collision from the relative positions between the nearby vehicle and the host vehicle and warns the driver of the collision possibility, and the like.
In Patent Literature 1, as a mobile object which transmits the position information, only a vehicle is assumed. However, in recent years, a mobile terminal having a terminal GPS function such as, e.g., a smartphone or a tablet has been widely used. Accordingly, a pedestrian, a bicycle, or the like carrying a mobile terminal of this type device may also become the mobile object that transmits the position information.
In view of such a background, a drive assist system which uses the position information of not only a vehicle, but also a mobile object other than the vehicle may be considered. That is, a drive assist device which displays the relative positions of a nearby mobile object and a host vehicle using the position information of different types of nearby mobile objects such as a vehicle and a pedestrian, or a drive assist device which determines the probability of a collision or the like from the relative positions of the nearby mobile objects and the host vehicle and warns a driver of the collision probability may be considered.
However, when the position information of a mobile object other than a vehicle, such as a pedestrian, is subjected to map matching in the same manner as with a vehicle, it follows that, e.g., a pedestrian who is originally present at a position away from a road seems to be present on the road.
When the drive assist device described above displays the position of the nearby mobile object on the basis of the corrected position information that shows an erroneous position, the pedestrian who is actually not present on the road is displayed in such a manner as to be seemingly present on the road. This may unintentionally confuse the driver.